1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95 29.\" $FreeBSD: src/lib/libc/gen/sysctl.3,v 1.33.2.13 2002/04/07 04:57:14 dd Exp $ 30.\" 31.Dd May 25, 2021 32.Dt SYSCTL 3 33.Os 34.Sh NAME 35.Nm sysctl , 36.Nm sysctlbyname , 37.Nm sysctlnametomib 38.Nd get or set system information 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In sys/types.h 43.In sys/sysctl.h 44.Ft int 45.Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 46.Ft int 47.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 48.Ft int 49.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 50.Sh DESCRIPTION 51The 52.Fn sysctl 53function retrieves system information and allows processes with 54appropriate privileges to set system information. 55The information available from 56.Fn sysctl 57consists of integers, strings, and tables. 58Information may be retrieved and set from the command interface 59using the 60.Xr sysctl 8 61utility. 62.Pp 63Unless explicitly noted below, 64.Fn sysctl 65returns a consistent snapshot of the data requested. 66Consistency is obtained by locking the destination 67buffer into memory so that the data may be copied out without blocking. 68Calls to 69.Fn sysctl 70are serialized to avoid deadlock. 71.Pp 72The state is described using a 73.Dq Management Information Base (MIB) 74style name, listed in 75.Fa name , 76which is a 77.Fa namelen 78length array of integers. 79.Pp 80The 81.Fn sysctlbyname 82function accepts an ASCII representation of the name and internally 83looks up the integer name vector. Apart from that, it behaves the same 84as the standard 85.Fn sysctl 86function. 87.Pp 88The information is copied into the buffer specified by 89.Fa oldp . 90The size of the buffer is given by the location specified by 91.Fa oldlenp 92before the call, 93and that location gives the amount of data copied after a successful call 94and after a call that returns with the error code 95.Er ENOMEM . 96If the amount of data available is greater 97than the size of the buffer supplied, 98the call supplies as much data as fits in the buffer provided 99and returns with the error code 100.Er ENOMEM . 101If the old value is not desired, 102.Fa oldp 103and 104.Fa oldlenp 105should be set to NULL. 106.Pp 107The size of the available data can be determined by calling 108.Fn sysctl 109with a NULL parameter for 110.Fa oldp . 111The size of the available data will be returned in the location pointed to by 112.Fa oldlenp . 113For some operations, the amount of space may change often. 114For these operations, 115the system attempts to round up so that the returned size is 116large enough for a call to return the data shortly thereafter. 117.Pp 118To set a new value, 119.Fa newp 120is set to point to a buffer of length 121.Fa newlen 122from which the requested value is to be taken. 123If a new value is not to be set, 124.Fa newp 125should be set to NULL and 126.Fa newlen 127set to 0. 128.Pp 129The 130.Fn sysctlnametomib 131function accepts an ASCII representation of the name, 132looks up the integer name vector, 133and returns the numeric representation in the mib array pointed to by 134.Fa mibp . 135The number of elements in the mib array is given by the location specified by 136.Fa sizep 137before the call, 138and that location gives the number of entries copied after a successful call. 139The resulting 140.Fa mib 141and 142.Fa size 143may be used in subsequent 144.Fn sysctl 145calls to get the data associated with the requested ASCII name. 146This interface is intended for use by applications that want to 147repeatedly request the same variable (the 148.Fn sysctl 149function runs in about a third the time as the same request made via the 150.Fn sysctlbyname 151function). 152The 153.Fn sysctlnametomib 154function is also useful for fetching mib prefixes and then adding 155a final component. 156For example, to fetch process information 157for processes with pid's less than 100: 158.Pp 159.Bd -literal -offset indent -compact 160int i, mib[4]; 161size_t len; 162struct kinfo_proc kp; 163 164/* Fill out the first three components of the mib */ 165len = 4; 166sysctlnametomib("kern.proc.pid", mib, &len); 167 168/* Fetch and print entries for pid's < 100 */ 169for (i = 0; i < 100; i++) { 170 mib[3] = i; 171 len = sizeof(kp); 172 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 173 perror("sysctl"); 174 else if (len > 0) 175 printkproc(&kp); 176} 177.Ed 178.Pp 179The top level names are defined with a CTL_ prefix in 180.In sys/sysctl.h , 181and are as follows. 182The next and subsequent levels down are found in the include files 183listed here, and described in separate sections below. 184.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 185.It Sy "Name" Ta Sy "Next level names" Ta Sy "Description" 186.It Dv CTL_DEBUG Ta "sys/sysctl.h" Ta "Debugging" 187.It Dv CTL_VFS Ta "sys/mount.h" Ta "Filesystem" 188.It Dv CTL_HW Ta "sys/sysctl.h" Ta "Generic CPU, I/O" 189.It Dv CTL_KERN Ta "sys/sysctl.h" Ta "High kernel limits" 190.It Dv CTL_MACHDEP Ta "sys/sysctl.h" Ta "Machine dependent" 191.It Dv CTL_NET Ta "sys/socket.h" Ta "Networking" 192.It Dv CTL_USER Ta "sys/sysctl.h" Ta "User-level" 193.It Dv CTL_VM Ta "vm/vm_param.h" Ta "Virtual memory" 194.El 195.Pp 196For example, the following retrieves the maximum number of processes allowed 197in the system: 198.Pp 199.Bd -literal -offset indent -compact 200int mib[2], maxproc; 201size_t len; 202 203mib[0] = CTL_KERN; 204mib[1] = KERN_MAXPROC; 205len = sizeof(maxproc); 206sysctl(mib, 2, &maxproc, &len, NULL, 0); 207.Ed 208.Pp 209To retrieve the standard search path for the system utilities: 210.Pp 211.Bd -literal -offset indent -compact 212int mib[2]; 213size_t len; 214char *p; 215 216mib[0] = CTL_USER; 217mib[1] = USER_CS_PATH; 218sysctl(mib, 2, NULL, &len, NULL, 0); 219p = malloc(len); 220sysctl(mib, 2, p, &len, NULL, 0); 221.Ed 222.Ss CTL_DEBUG 223The debugging variables vary from system to system. 224A debugging variable may be added or deleted without need to recompile 225.Fn sysctl 226to know about it. 227Each time it runs, 228.Fn sysctl 229gets the list of debugging variables from the kernel and 230displays their current values. 231The system defines twenty 232.Vt struct ctldebug 233variables named 234.Nm debug0 235through 236.Nm debug19 . 237They are declared as separate variables so that they can be 238individually initialized at the location of their associated variable. 239The loader prevents multiple use of the same variable by issuing errors 240if a variable is initialized in more than one place. 241For example, to export the variable 242.Nm dospecialcheck 243as a debugging variable, the following declaration would be used: 244.Bd -literal -offset indent -compact 245int dospecialcheck = 1; 246struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 247.Ed 248.Ss CTL_VFS 249A distinguished second level name, VFS_GENERIC, 250is used to get general information about all filesystems. 251One of its third level identifiers is VFS_MAXTYPENUM 252that gives the highest valid filesystem type number. 253Its other third level identifier is VFS_CONF that 254returns configuration information about the filesystem 255type given as a fourth level identifier (see 256.Xr getvfsbyname 3 257as an example of its use). 258The remaining second level identifiers are the 259filesystem type number returned by a 260.Xr statfs 2 261call or from VFS_CONF. 262The third level identifiers available for each filesystem 263are given in the header file that defines the mount 264argument structure for that filesystem. 265.Ss CTL_HW 266The string and integer information available for the 267.Dv CTL_HW 268level 269is detailed below. 270The changeable column shows whether a process with appropriate 271privilege may change the value. 272.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 273.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 274.It Dv HW_MACHINE Ta "string" Ta "no" 275.It Dv HW_MODEL Ta "string" Ta "no" 276.It Dv HW_NCPU Ta "integer" Ta "no" 277.It Dv HW_BYTEORDER Ta "integer" Ta "no" 278.It Dv HW_PHYSMEM Ta "integer" Ta "no" 279.It Dv HW_USERMEM Ta "integer" Ta "no" 280.It Dv HW_PAGESIZE Ta "integer" Ta "no" 281.It Dv HW_FLOATINGPT Ta "integer" Ta "no" 282.It Dv HW_MACHINE_ARCH Ta "string" Ta "no" 283.It Dv HW_MACHINE_PLATFORM Ta "string" Ta "no" 284.\".It Dv HW_DISKNAMES Ta "integer" Ta "no" 285.\".It Dv HW_DISKSTATS Ta "integer" Ta "no" 286.It Dv HW_SENSORS Ta "node" Ta "not applicable" 287.El 288.Bl -tag -width 6n 289.It Dv HW_MACHINE 290The machine class. 291.It Dv HW_MODEL 292The machine model 293.It Dv HW_NCPU 294The number of cpus. 295.It Dv HW_BYTEORDER 296The byteorder (4321, or 1234). 297.It Dv HW_PHYSMEM 298The bytes of physical memory. 299.It Dv HW_USERMEM 300The bytes of non-kernel memory. 301.It Dv HW_PAGESIZE 302The software page size. 303.It Dv HW_FLOATINGPT 304Nonzero if the floating point support is in hardware. 305.It Dv HW_MACHINE_ARCH 306The machine dependent architecture type. 307.It Dv HW_MACHINE_PLATFORM 308The platform architecture type. 309.\".It Dv HW_DISKNAMES 310.\".It Dv HW_DISKSTATS 311.It Dv HW_SENSORS 312Third level comprises an array of 313.Vt "struct sensordev" 314structures containing information about devices 315that may attach hardware monitoring sensors. 316.Pp 317Third, fourth and fifth levels together comprise an array of 318.Vt "struct sensor" 319structures containing snapshot readings of hardware monitoring sensors. 320In such usage, third level indicates the numerical representation 321of the sensor device name to which the sensor is attached 322(device's 323.Va xname 324and number shall be matched with the help of 325.Vt "struct sensordev" 326structure above), 327fourth level indicates sensor type and 328fifth level is an ordinal sensor number (unique to 329the specified sensor type on the specified sensor device). 330.Pp 331The 332.Vt sensordev 333and 334.Vt sensor 335structures 336and 337.Vt sensor_type 338enumeration 339are defined in 340.In sys/sensors.h . 341.El 342.Ss CTL_KERN 343The string and integer information available for the 344.Dv CTL_KERN 345level 346is detailed below. 347The changeable column shows whether a process with appropriate 348privilege may change the value. 349The types of data currently available are process information, 350system vnodes, the open file entries, routing table entries, 351virtual memory statistics, load average history, and clock rate 352information. 353.Bl -column "KERNXMAXPOSIXLOCKSPERUIDXXX" "struct clockrateXXX" -offset indent 354.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 355.It Dv KERN_ARGMAX Ta "integer" Ta "no" 356.It Dv KERN_BOOTFILE Ta "string" Ta "yes" 357.It Dv KERN_BOOTTIME Ta "struct timespec" Ta "no" 358.It Dv KERN_CLOCKRATE Ta "struct clockinfo" Ta "no" 359.It Dv KERN_FILE Ta "struct kinfo_file" Ta "no" 360.It Dv KERN_HOSTID Ta "integer" Ta "yes" 361.It Dv KERN_HOSTNAME Ta "string" Ta "yes" 362.It Dv KERN_JOB_CONTROL Ta "integer" Ta "no" 363.It Dv KERN_MAXFILES Ta "integer" Ta "yes" 364.It Dv KERN_MAXFILESPERPROC Ta "integer" Ta "yes" 365.It Dv KERN_MAXPOSIXLOCKSPERUID Ta "integer" Ta "yes" 366.It Dv KERN_MAXPROC Ta "integer" Ta "no" 367.It Dv KERN_MAXPROCPERUID Ta "integer" Ta "yes" 368.It Dv KERN_MAXVNODES Ta "integer" Ta "yes" 369.It Dv KERN_NGROUPS Ta "integer" Ta "no" 370.It Dv KERN_NISDOMAINNAME Ta "string" Ta "yes" 371.It Dv KERN_OSRELDATE Ta "integer" Ta "no" 372.It Dv KERN_OSRELEASE Ta "string" Ta "no" 373.It Dv KERN_OSREV Ta "integer" Ta "no" 374.It Dv KERN_OSTYPE Ta "string" Ta "no" 375.It Dv KERN_POSIX1 Ta "integer" Ta "no" 376.It Dv KERN_PROC Ta "struct kinfo_proc" Ta "no" 377.It Dv KERN_SAVED_IDS Ta "integer" Ta "no" 378.It Dv KERN_SECURELVL Ta "integer" Ta "raise only" 379.It Dv KERN_VERSION Ta "string" Ta "no" 380.It Dv KERN_VNODE Ta "struct vnode" Ta "no" 381.El 382.Bl -tag -width 6n 383.It Dv KERN_ARGMAX 384The maximum bytes of argument to 385.Xr execve 2 . 386.It Dv KERN_BOOTFILE 387The full pathname of the file from which the kernel was loaded. 388.It Dv KERN_BOOTTIME 389A 390.Vt struct timespec 391structure is returned. 392This structure contains the time that the system was booted. 393.It Dv KERN_CLOCKRATE 394A 395.Vt struct clockinfo 396structure is returned. 397This structure contains the clock, statistics clock and profiling clock 398frequencies, the number of micro-seconds per hz tick and the skew rate. 399.It Dv KERN_FILE 400Return the entire file table. 401The returned data consists of an array of 402.Vt struct kinfo_file , 403whose size depends on the current number of such objects in the system. 404.It Dv KERN_HOSTID 405Get or set the host id. 406.It Dv KERN_HOSTNAME 407Get or set the hostname. 408.It Dv KERN_JOB_CONTROL 409Return 1 if job control is available on this system, otherwise 0. 410.It Dv KERN_MAXFILES 411The maximum number of files that may be open in the system. 412.It Dv KERN_MAXFILESPERPROC 413The maximum number of files that may be open for a single process. 414This limit only applies to processes with an effective uid of nonzero 415at the time of the open request. 416Files that have already been opened are not affected if the limit 417or the effective uid is changed. 418.It Dv KERN_MAXPROC 419The maximum number of concurrent processes the system will allow. 420.It Dv KERN_MAXPROCPERUID 421The maximum number of concurrent processes the system will allow 422for a single effective uid. 423This limit only applies to processes with an effective uid of nonzero 424at the time of a fork request. 425Processes that have already been started are not affected if the limit 426is changed. 427.It Dv KERN_MAXVNODES 428The maximum number of vnodes available on the system. 429.It Dv KERN_NGROUPS 430The maximum number of supplemental groups. 431.It Dv KERN_NISDOMAINNAME 432The name of the current YP/NIS domain. 433.It Dv KERN_OSRELDATE 434The same as 435.Dv KERN_OSREV . 436.It Dv KERN_OSRELEASE 437The system release string. 438.It Dv KERN_OSREV 439The system revision number, in base-10 format 440.Ar M Ns Ar mmm Ns Ar pp , 441representing the following components: 442.Bl -column "Code" "Component" -offset indent 443.It Sy "Code" Ta Sy "Component" 444.It M Ta major 445.It mmm Ta minor 446.It pp Ta patch 447.El 448.Pp 449This is 450.Dv __DragonFly_version 451from 452.In sys/param.h . 453.Pp 454The minor component is an 455.Sy even Ns -number for release and 456.Sy odd Ns -number for development branches. 457.It Dv KERN_OSTYPE 458The system type string. 459.It Dv KERN_POSIX1 460The version of 461.St -p1003.1 462with which the system 463attempts to comply. 464.It Dv KERN_PROC 465Return selected information about specific running processes. 466.Pp 467For the following names, an array of 468.Vt struct kinfo_proc 469structures is returned, 470whose size depends on the current number of such objects in the system. 471Adding the flag 472.Dv KERN_PROC_FLAG_LWP 473to the third level name signals that information about all 474light weight processes of the selected processes should be returned. 475.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 476.It Sy "Third level name" Ta Sy "Fourth level is:" 477.It Dv KERN_PROC_ALL Ta "None" 478.It Dv KERN_PROC_PID Ta "A process ID" 479.It Dv KERN_PROC_PGRP Ta "A process group" 480.It Dv KERN_PROC_TTY Ta "A tty device" 481.It Dv KERN_PROC_UID Ta "A user ID" 482.It Dv KERN_PROC_RUID Ta "A real user ID" 483.El 484.Pp 485For the following names, a NUL-terminated string is returned. 486.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 487.It Sy "Third level name" Ta Sy "Fourth level is:" 488.It Dv KERN_PROC_ARGS Ta "A process ID" 489.It Dv KERN_PROC_CWD Ta "A process ID" 490.It Dv KERN_PROC_PATHNAME Ta "A process ID" 491.El 492.Pp 493The variables are as follows: 494.Bl -tag -width 6n 495.It Dv KERN_PROC_ARGS 496Returns the command line argument array of a process, in a flattened form, 497i.e. NUL-terminated arguments follow each other. 498A process can set its own process title by changing this value. 499.It Dv KERN_PROC_CWD 500Returns the current working directory of a process. 501.It Dv KERN_PROC_PATHNAME 502Returns the path of a process' text file. 503A process ID of 504.Li \-1 505implies the current process. 506.El 507.It Dv KERN_SAVED_IDS 508Returns 1 if saved set-group and saved set-user ID is available. 509.It Dv KERN_SECURELVL 510The system security level. 511This level may be raised by processes with appropriate privilege. 512It may not be lowered. 513.It Dv KERN_VERSION 514The system version string. 515.It Dv KERN_VNODE 516Return the entire vnode table. 517Note, the vnode table is not necessarily a consistent snapshot of 518the system. 519The returned data consists of an array whose size depends on the 520current number of such objects in the system. 521Each element of the array contains the kernel address of a vnode 522.Vt struct vnode * 523followed by the vnode itself 524.Vt struct vnode . 525.El 526.Ss CTL_MACHDEP 527The set of variables defined is architecture dependent. 528The following variables are defined for the x86_64 architecture. 529.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 530.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 531.It Dv CPU_CONSDEV Ta "dev_t" Ta "no" 532.It Dv CPU_ADJKERNTZ Ta "int" Ta "yes" 533.It Dv CPU_DISRTCSET Ta "int" Ta "yes" 534.It Dv CPU_BOOTINFO Ta "struct bootinfo" Ta "no" 535.It Dv CPU_WALLCLOCK Ta "int" Ta "yes" 536.El 537.Ss CTL_NET 538The string and integer information available for the 539.Dv CTL_NET 540level is detailed below. 541The changeable column shows whether a process with appropriate 542privilege may change the value. 543.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 544.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 545.It Dv PF_ROUTE Ta "routing messages" Ta "no" 546.It Dv PF_INET Ta "IPv4 values" Ta "yes" 547.It Dv PF_INET6 Ta "IPv6 values" Ta "yes" 548.El 549.Bl -tag -width 6n 550.It Dv PF_ROUTE 551Return the entire routing table or a subset of it. 552The data is returned as a sequence of routing messages (see 553.Xr route 4 554for the header file, format and meaning). 555The length of each message is contained in the message header. 556.Pp 557The third level name is a protocol number, which is currently always 0. 558The fourth level name is an address family, which may be set to 0 to 559select all address families. 560The fifth and sixth level names are as follows: 561.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 562.It Sy "Fifth level name" Ta Sy "Sixth level is:" 563.It Dv NET_RT_FLAGS Ta "rtflags" 564.It Dv NET_RT_DUMP Ta "None" 565.It Dv NET_RT_IFLIST Ta "None" 566.El 567.It Dv PF_INET 568Get or set various global information about the IPv4 569.Pq Internet Protocol version 4 . 570The third level name is the protocol. 571The fourth level name is the variable name. 572The currently defined protocols and names are: 573.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 574.It Sy "Protocol" Ta Sy "Variable" Ta Sy "Type" Ta Sy "Changeable" 575.It icmp Ta bmcastecho Ta integer Ta yes 576.It icmp Ta maskrepl Ta integer Ta yes 577.It ip Ta forwarding Ta integer Ta yes 578.It ip Ta redirect Ta integer Ta yes 579.It ip Ta ttl Ta integer Ta yes 580.It udp Ta checksum Ta integer Ta yes 581.El 582.Pp 583The variables are as follows: 584.Bl -tag -width 6n 585.It Li icmp.bmcastecho 586Returns 1 if an ICMP echo request to a broadcast or multicast address is 587to be answered. 588.It Li icmp.maskrepl 589Returns 1 if ICMP network mask requests are to be answered. 590.It Li ip.forwarding 591Returns 1 when IP forwarding is enabled for the host, 592meaning that the host is acting as a router. 593.It Li ip.redirect 594Returns 1 when ICMP redirects may be sent by the host. 595This option is ignored unless the host is routing IP packets, 596and should normally be enabled on all systems. 597.It Li ip.ttl 598The maximum time-to-live (hop count) value for an IP packet sourced by 599the system. 600This value applies to normal transport protocols, not to ICMP. 601.It Li udp.checksum 602Returns 1 when UDP checksums are being computed and checked. 603Disabling UDP checksums is strongly discouraged. 604.El 605.It Dv PF_INET6 606Get or set various global information about IPv6 607.Pq Internet Protocol version 6 . 608The third level name is the protocol. 609The fourth level name is the variable name. 610.Pp 611For variables 612.Li net.inet6.* , 613please refer to 614.Xr inet6 4 . 615.El 616.Ss CTL_USER 617The string and integer information available for the 618.Dv CTL_USER 619level is detailed below. 620The changeable column shows whether a process with appropriate 621privilege may change the value. 622.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 623.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 624.It Dv USER_BC_BASE_MAX Ta integer Ta no 625.It Dv USER_BC_DIM_MAX Ta integer Ta no 626.It Dv USER_BC_SCALE_MAX Ta integer Ta no 627.It Dv USER_BC_STRING_MAX Ta integer Ta no 628.It Dv USER_COLL_WEIGHTS_MAX Ta integer Ta no 629.It Dv USER_CS_PATH Ta string Ta no 630.It Dv USER_EXPR_NEST_MAX Ta integer Ta no 631.It Dv USER_LINE_MAX Ta integer Ta no 632.It Dv USER_POSIX2_CHAR_TERM Ta integer Ta no 633.It Dv USER_POSIX2_C_BIND Ta integer Ta no 634.It Dv USER_POSIX2_C_DEV Ta integer Ta no 635.It Dv USER_POSIX2_FORT_DEV Ta integer Ta no 636.It Dv USER_POSIX2_FORT_RUN Ta integer Ta no 637.It Dv USER_POSIX2_LOCALEDEF Ta integer Ta no 638.It Dv USER_POSIX2_SW_DEV Ta integer Ta no 639.It Dv USER_POSIX2_UPE Ta integer Ta no 640.It Dv USER_POSIX2_VERSION Ta integer Ta no 641.It Dv USER_RE_DUP_MAX Ta integer Ta no 642.It Dv USER_STREAM_MAX Ta integer Ta no 643.It Dv USER_TZNAME_MAX Ta integer Ta no 644.El 645.Bl -tag -width 6n 646.It Dv USER_BC_BASE_MAX 647The maximum ibase/obase values in the 648.Xr bc 1 649utility. 650.It Dv USER_BC_DIM_MAX 651The maximum array size in the 652.Xr bc 1 653utility. 654.It Dv USER_BC_SCALE_MAX 655The maximum scale value in the 656.Xr bc 1 657utility. 658.It Dv USER_BC_STRING_MAX 659The maximum string length in the 660.Xr bc 1 661utility. 662.It Dv USER_COLL_WEIGHTS_MAX 663The maximum number of weights that can be assigned to any entry of the 664.Dv LC_COLLATE 665order keyword in the locale definition file. 666.It Dv USER_CS_PATH 667Return a value for the 668.Ev PATH 669environment variable that finds all the standard utilities. 670.It Dv USER_EXPR_NEST_MAX 671The maximum number of expressions that can be nested within 672parenthesis by the 673.Xr expr 1 674utility. 675.It Dv USER_LINE_MAX 676The maximum length in bytes of a text-processing utility's input line. 677.It Dv USER_POSIX2_CHAR_TERM 678Return 1 if the system supports at least one terminal type capable of 679all operations described in 680.St -p1003.2 , 681otherwise 0. 682.It Dv USER_POSIX2_C_BIND 683Return 1 if the system's C-language development facilities support the 684C-Language Bindings Option, otherwise 0. 685.It Dv USER_POSIX2_C_DEV 686Return 1 if the system supports the C-Language Development Utilities Option, 687otherwise 0. 688.It Dv USER_POSIX2_FORT_DEV 689Return 1 if the system supports the FORTRAN Development Utilities Option, 690otherwise 0. 691.It Dv USER_POSIX2_FORT_RUN 692Return 1 if the system supports the FORTRAN Runtime Utilities Option, 693otherwise 0. 694.It Dv USER_POSIX2_LOCALEDEF 695Return 1 if the system supports the creation of locales, otherwise 0. 696.It Dv USER_POSIX2_SW_DEV 697Return 1 if the system supports the Software Development Utilities Option, 698otherwise 0. 699.It Dv USER_POSIX2_UPE 700Return 1 if the system supports the User Portability Utilities Option, 701otherwise 0. 702.It Dv USER_POSIX2_VERSION 703The version of 704.St -p1003.2 705with which the system attempts to comply. 706.It Dv USER_RE_DUP_MAX 707The maximum number of repeated occurrences of a regular expression 708permitted when using interval notation. 709.It Dv USER_STREAM_MAX 710The minimum maximum number of streams that a process may have open 711at any one time. 712.It Dv USER_TZNAME_MAX 713The minimum maximum number of types supported for the name of a timezone. 714.El 715.Ss CTL_VM 716The string and integer information available for the 717.Dv CTL_VM 718level is detailed below. 719The changeable column shows whether a process with appropriate 720privilege may change the value. 721.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 722.It Sy "Second level name" Ta Sy "Type" Ta Sy "Changeable" 723.It Dv VM_LOADAVG Ta struct loadavg Ta no 724.It Dv VM_METER Ta struct vmtotal Ta no 725.It Dv VM_PAGEOUT_ALGORITHM Ta integer Ta yes 726.It Dv VM_SWAPPING_ENABLED Ta integer Ta maybe 727.It Dv VM_V_CACHE_MAX Ta integer Ta yes 728.It Dv VM_V_CACHE_MIN Ta integer Ta yes 729.It Dv VM_V_FREE_MIN Ta integer Ta yes 730.It Dv VM_V_FREE_RESERVED Ta integer Ta yes 731.It Dv VM_V_FREE_TARGET Ta integer Ta yes 732.It Dv VM_V_INACTIVE_TARGET Ta integer Ta yes 733.It Dv VM_V_PAGEOUT_FREE_MIN Ta integer Ta yes 734.El 735.Bl -tag -width 6n 736.It Dv VM_LOADAVG 737Return the load average history. 738The returned data consists of a 739.Vt struct loadavg . 740.It Dv VM_METER 741Return the system wide virtual memory statistics. 742The returned data consists of a 743.Vt struct vmtotal . 744.It Dv VM_PAGEOUT_ALGORITHM 7450 if the statistics-based page management algorithm is in use 746or 1 if the near-LRU algorithm is in use. 747.It Dv VM_SWAPPING_ENABLED 7481 if process swapping is enabled or 0 if disabled. This variable is 749permanently set to 0 if the kernel was built with swapping disabled. 750.It Dv VM_V_CACHE_MAX 751Maximum desired size of the cache queue. 752.It Dv VM_V_CACHE_MIN 753Minimum desired size of the cache queue. If the cache queue size 754falls very far below this value, the pageout daemon is awakened. 755.It Dv VM_V_FREE_MIN 756Minimum amount of memory (cache memory plus free memory) 757required to be available before a process waiting on memory will be 758awakened. 759.It Dv VM_V_FREE_RESERVED 760Processes will awaken the pageout daemon and wait for memory if the 761number of free and cached pages drops below this value. 762.It Dv VM_V_FREE_TARGET 763The total amount of free memory (including cache memory) that the 764pageout daemon tries to maintain. 765.It Dv VM_V_INACTIVE_TARGET 766The desired number of inactive pages that the pageout daemon should 767achieve when it runs. Inactive pages can be quickly inserted into 768process address space when needed. 769.It Dv VM_V_PAGEOUT_FREE_MIN 770If the amount of free and cache memory falls below this value, the 771pageout daemon will enter "memory conserving mode" to avoid deadlock. 772.El 773.Sh RETURN VALUES 774.Rv -std 775.Sh FILES 776.Bl -tag -width ".In netinet/icmp_var.h" -compact 777.It In sys/sysctl.h 778definitions for top level identifiers, second level kernel and hardware 779identifiers, and user level identifiers 780.It In sys/socket.h 781definitions for second level network identifiers 782.It In sys/gmon.h 783definitions for third level profiling identifiers 784.It In vm/vm_param.h 785definitions for second level virtual memory identifiers 786.It In netinet/in.h 787definitions for third level IPv4/IPv6 identifiers and 788fourth level IPv4/v6 identifiers 789.It In netinet/icmp_var.h 790definitions for fourth level ICMP identifiers 791.It In netinet/icmp6.h 792definitions for fourth level ICMPv6 identifiers 793.It In netinet/udp_var.h 794definitions for fourth level UDP identifiers 795.El 796.Sh ERRORS 797The following errors may be reported: 798.Bl -tag -width Er 799.It Bq Er EFAULT 800The buffer 801.Fa name , 802.Fa oldp , 803.Fa newp , 804or length pointer 805.Fa oldlenp 806contains an invalid address. 807.It Bq Er EINVAL 808The 809.Fa name 810array is less than two or greater than 811.Dv CTL_MAXNAME . 812.It Bq Er EINVAL 813A non-null 814.Fa newp 815is given and its specified length in 816.Fa newlen 817is too large or too small. 818.It Bq Er ENOMEM 819The length pointed to by 820.Fa oldlenp 821is too short to hold the requested value. 822.It Bq Er ENOTDIR 823The 824.Fa name 825array specifies an intermediate rather than terminal name. 826.It Bq Er EISDIR 827The 828.Fa name 829array specifies a terminal name, but the actual name is not terminal. 830.It Bq Er ENOENT 831The 832.Fa name 833array specifies a value that is unknown. 834.It Bq Er EPERM 835An attempt is made to set a read-only value. 836.It Bq Er EPERM 837A process without appropriate privilege attempts to set a value. 838.El 839.Sh SEE ALSO 840.Xr sysconf 3 , 841.Xr sysctl 8 842.Sh HISTORY 843The 844.Fn sysctl 845function first appeared in 846.Bx 4.4 . 847